Electroless plating membranes

The pores in a commercially available polycarbonate filtration membrane (Poretics) were used as templates to form the nanotubules (pore diameter = 50 nm pore density = 6 X 10 pores cm thickness = 6 pm). As before, the electrolessly plated Au deposits both on the pore walls and the membrane faces [71]. The gold surface layers on the membrane faces allow us to make electrical contact to the Au nanotubules within the pores. The thickness of the gold layers deposited on the pore walls can be controlled... 

The electroless plating method described above was used to prepare membranes that contain cylindrical gold nanotubules, which span the complete thickness of the membrane. As before, polycarbonate filtration membranes with cylindrical, monodisperse pores (Poretics, 6 [im thick, pore dia. = 30 nm) were used as the templates. The inside diameter (i.d.) of the nanotubules can be varied by varying the plating time (Fig. 14). At sufficiently long plating times, Au nanotubules with i.d.s of molecular dimensions (<1 nm) are obtained [106],... 

The heavy metals used in printed circuit electroless plating (copper and nickel) are in chelated form (chemically "tied-up" in an organic matrix). The plating baths are more unstable than electroplating baths, thereby resulting in more frequent "dumping". As a result, waste treatment requirements in printed circuit manufacturing operations present special problems and opportunities for membrane separation processes. 

Tanaka D.A.P., Llosa Tanco M.A., Niwa Si., Wakui Y., Mizukami F., Namba T., Suzuki T.M. Preparation of palladium and silver alloy membrane on a porous a-alumina tube via simultaneous electroless plating. J.Membr.Sci 2005 247 21-27. 

Gold nanotubes have been made by electroless plating within the 220 nm diameter pores of a polycarbonate membrane.66... 

The manufacture of dense metal membranes or thin films can be effected by a number of processes casting/rolling, vapor deposition by physical and chemical means, electroplating (or electroforming) and electroless plating. By far, casting in combination with rolling is the predominant preparation and fabrication technique. It is noted that many of these processes have been demonstrated with palladium and its alloys because of their low oxidation propensity. Preparation of dense metal membranes is summarized in some detail as follows. 

Kikuchi, E., Menoto, Y., Kajiwara, M., Uemiya, S., Kojima, T. (2000). Steam reforming of methane in membrane reactors comparison of electroless-plating and CVD membranes and catalyst packing methods. Catalysis Today 56, 75-81. 

The methods for preparation of nonporous composite membrane catalyst are discussed in Ref. 10. The porous stainless steel sheets were covered with a dense palladium alloy film by magnetron sputtering [113] or by corolling of palladium alloy foil and porous steel sheet. The electroless plating of palladium or palladium alloy on stainless steel [114] or on porous alumina ceramic [115,116] gives the composite membranes with an ultrathin, dense palladium top layer. 

Gao, H., Lin, J.Y.S., Li, Y., and Zhang, B. Electroless plating synthesis, characterization and permeation properties of Pd-Cu membranes supported on Zr02 modified porous stainless steel. Journal of Membrane Science, 2005, 265, 142-152. 

Palladium and palladium-silver alloy membranes on porous alumina tubes were prepared by means of simultaneous and sequential electroless plating techniques [234], The membrane reactor was used for the direct formation of hydrogen peroxide by catalytic reaction of H2 and 02 at 293 K. The concentration of H202 increased with increases in the transmembrane partial pressure gradient of H2. A high concentration of H202 was obtained with a membrane that consisted of a palladium layer on the outer surface, porous alumina in the middle, and a palladium-silver alloy layer on the inside. 

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